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Multidrug-Resistant Tuberculosis (TB)

Topic Overview

Multidrug-resistant tuberculosis (MDR-TB) occurs when the
bacteria are resistant to at least isoniazid and rifampin. This means that
these medicines are unable to kill the bacteria. The reasons
antibiotic resistance occurs include:

Medicine treatment failure. Failure to complete the
entire course of treatment is the major cause of multidrug-resistant TB. If all
of the medicines prescribed are not taken as directed, the weaker bacteria are
killed, but some stronger, more resistant bacteria survive. These resistant
bacteria can grow and cause TB disease that is difficult to cure.

Inadequate TB control measures. People with
multidrug-resistant TB disease can infect others with drug-resistant bacteria.
This has happened in prisons, hospitals, and homeless shelters.

People who have resistant disease are at increased risk
for dying of TB, especially if they also are infected with the
human immunodeficiency virus (HIV). People who are at
highest risk for developing multidrug-resistant TB are those who:

Have a weakened immune system, such as people who
are infected with HIV, have
AIDS, or have cancer.

Have been in close
contact with a person who is infected with multidrug-resistant
TB.

Do not take their prescribed medicine regularly or do not take
all of their medicine.

Develop TB disease again after having taken
TB medicine in the past.

Come from areas where TB is common, such
as Southeast Asia, Africa, or Latin America.

To reduce the problem of drug resistance, doctors now use the
following guidelines to treat all people who have resistant TB:1

Almost everyone begins treatment of TB with four
different medicines, which are taken until a culture test shows no bacteria.
Then, two medicines are taken for 4 to 7 months. Young children and pregnant
women may begin TB treatment using only three medicines.

A health
professional must watch the person take every dose of medicine. This is called
directly observed therapy (DOT) and may mean a daily
office or home visit. DOT does help make sure that all of the medicines are
taken, and it has raised cure rates.

Whenever possible, a person is
treated at a center that specializes in treating multidrug-resistant TB.

A rare type of MDR-TB is called extensively drug-resistant
tuberculosis (XDR-TB). This type of TB is resistant to isoniazid, rifampin, and
several other medicines used to treat TB. And some TB bacteria have become resistant to all of the antibiotics commonly used to treat TB. This is sometimes called totally resistant tuberculosis (TDR-TB).2

Related Information

References

Citations

American Thoracic Society, Centers for Disease Control
and Prevention, Infectious Diseases Society of America (2003). Treatment of
tuberculosis. American Journal of Respiratory and Critical Care Medicine, 167(4): 603–662.

American Thoracic Society, Centers for Disease Control
and Prevention, Infectious Diseases Society of America (2003). Treatment of
tuberculosis. American Journal of Respiratory and Critical Care Medicine, 167(4): 603–662.

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